Organic semiconductor radiation/light sensor and radiation/light detector

ABSTRACT

There is provided a high-sensitivity organic semiconductor radiation/light sensor and a radiation/light detector which can detect rays in real time. In the high-sensitivity organic semiconductor radiation/light sensor, a signal amplification wire  2  is embedded in an organic semiconductor  1 . Carriers created by passage of radiation or light are avalanche-amplified by a high electric field generated near the signal amplification wire  2  by means of applying a high voltage to the signal amplification wire  2 , thus dramatically improving detection efficiency of rays. Hence, even rays exhibiting low energy loss capability can be detected in real time with high sensitivity.

CROSS REFERENCE TO PROIR APPLICATIONS

This application is the U.S. national phase application of InternationalApplication No. PCT/JP2006/320925, filed Oct. 20, 2006,which claimspriority from Japanese Patent Application No. 2006-030324, filed Feb. 7,2006. Both applications are incorporated herein by reference in theirentirety. The International Application was published in Japanese onAug. 16, 2007 as WO 2007/091352 under PCT Article 21(2).

TECHNICAL FIELD

The present invention relates to an organic semiconductorradiation/light sensor and a radiation/light detector using the same.

BACKGROUND ART

In general, when radiation comprising charged particles such as rays orrays passes through matter, the radiation loses energy by ionizing,exciting and dissociating atoms and molecules which exist in the matter.At the same time, the energy thus lost is converted into thermal motionenergy, or transformed into electromagnetic energy to be discharged, orused as energy for creating charge carriers. Particularly, when theradiation is the one incident on a semiconductor, a significant part ofenergy lost from the incident particles is employed as energy forcreating a pair (a carrier) of an electron and a hole. With respect tonon-charged radiation such as X-rays, γ rays, neutron rays or the like,the same phenomena described above also occurs by an impact of secondaryelectrons generated in the interaction between the matter and theserays. Then, these carriers such as electrons and holes which have beengenerated are collected and captured as an electric signal by anelectric field and thereby radiation detection is generally performed bya semiconductor.

As semiconductors which generate the carriers along with passage ofradiation, there exist inorganic semiconductors represented by silicon,germanium crystal or the like and organic semiconductors represented bypolyaniline, polythiophene or the like.

By being produced as ultrapure crystal, the inorganic semiconductor isprovided with a reduced dark current and an excellent S/N ratio.Therefore, the inorganic semiconductor is being extensively employed asa real-time sensor in a radiation detector.

On the contrary, the organic semiconductor is low in cost as compared tothe inorganic semiconductor and is possessed of excellent propertiessuch as flexibility to be easily bent or the like. The organicsemiconductor, however, is presently poor in sensitivity as compared tothe inorganic semiconductor due to an impact of its impurities,nonuniformity of polymer molecular mass, etc. thus not yet having cometo practical use as a sensor of real-time radiation detection in theexisting circumstances.

-   Patent document 1: Japanese unexamined patent application    publication No.: H10-284748-   Patent document 2: Japanese unexamined patent application    publication No.: H5-3337-   Non-patent document 1: “Detectors for Particle Radiation Basis and    Application of Radiation Measurement” written by K. Kleinknecht,    translated by Kasuke Takahashi and Hajime Yoshiki, published by    Baifukan, 1987

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

As described above, an organic semiconductor has had the problem thatits sensitivity, i.e., its detection efficiency as a sensor for areal-time signal of radiation was low. So, when the organicsemiconductor has been employed, no success has ever been attained indetecting the radiation such as rays or the like that were less inenergy loss as compared to rays.

The organic semiconductor, however, is low in cost and is possessed offlexibility, and therefore if the organic semiconductor can be utilizedas a real-time radiation sensor capable of detecting rays, it isexpected that the organic semiconductor can contribute to development ofa new application of a semiconductor radiation detector, which has beenunimaginable in the case of utilizing the conventional inorganicsemiconductor, in such a manner as to permit a large-sized and curvedsemiconductor radiation detector to be comparatively easily made up andso on.

Therefore, it is an object of the present invention to provide anorganic semiconductor radiation sensor and a radiation detector whichcan detect rays in real time and are high sensitive.

Mean for Solving the Problem

As a result of various inspections in order to solve the problemdescribed above, it has been discovered that a fine conductive wire wasembedded in an organic semiconductor and then carriers created bypassage of radiation were avalanche-amplified by a high electric fieldcreated near the wire by means of applying a high voltage, therebyenabling rays to be detected. Thus, the present invention has beenaccomplished.

Therefore, an organic semiconductor radiation/light sensor according tothe present invention is characterized in that a signal amplificationwire is embedded in an organic semiconductor.

Further, the organic semiconductor radiation/light sensor according tothe present invention is characterized in that the signal amplificationwire is a metal wire.

Furthermore, the organic semiconductor radiation/light sensor accordingto the present invention is characterized in that the signalamplification wire is 10 to 100 m in diameter.

Moreover, the organic semiconductor radiation/light sensor according tothe present invention is characterized in that the organic semiconductoris any one of polyaniline, polythiophene, and polypyrrole.

Besides, the organic semiconductor radiation/light sensor according tothe present invention is characterized in that the organic semiconductoris substantially columnar and then the signal amplification wire isarranged substantially parallel with a bottom of the organicsemiconductor and further an electrode formed by deposition is providedon an upper surface of the organic semiconductor.

Further, the organic semiconductor radiation/light sensor according tothe present invention is characterized in that the organic semiconductoris substantially columnar and the signal amplification wire is arrangedon a central axis of the organic semiconductor and further an electrodeformed by deposition is provided across an entire circumference of alateral face of the organic semiconductor.

Furthermore, the organic semiconductor radiation/light sensor accordingto the present invention is characterized in that the organicsemiconductor is flat-plate-shaped and the signal amplification wire isarranged substantially parallel with an upper surface of the organicsemiconductor in a grid pattern and further an electrode formed bydeposition is provided across an entire upper surface of the organicsemiconductor.

An organic semiconductor radiation/light detector according to thepresent invention is characterized in that the detector is equipped withthe organic semiconductor radiation/light sensor embedded with thesignal amplification wire in an organic semiconductor.

Further, the organic semiconductor radiation/light detector according tothe present invention is characterized in that the signal amplificationwire is a metal wire,

Furthermore, the organic semiconductor radiation/light detectoraccording to the present invention is characterized in that the signalamplification wire is 10 to 100 m in diameter.

Moreover, the organic semiconductor radiation/light detector accordingto the present invention is characterized in that the organicsemiconductor is any one of polyaniline, polythiophene and polypyrrole.

Besides, the organic semiconductor radiation/light detector according tothe present invention is characterized in that the organic semiconductoris substantially columnar and then the signal amplification wire isarranged substantially parallel with a bottom of the organicsemiconductor and further an electrode formed by deposition is providedon the upper surface of the organic semiconductor.

Further, the organic semiconductor radiation/light detector according tothe present invention is characterized in that the organic semiconductoris substantially columnar and the signal amplification wire is arrangedon the central axis of the organic semiconductor and further theelectrode formed by deposition is provided across the entirecircumference of the lateral face of the organic semiconductor.

Furthermore, the organic semiconductor radiation/light sensor accordingto the present invention is characterized in that the organicsemiconductor is flat-plate-shaped and the signal amplification wiresare arranged substantially parallel with the upper surface of theorganic semiconductor in a grid pattern and further the electrode formedby deposition is provided across the entire upper surface of the organicsemiconductor.

Moreover, the organic semiconductor radiation/light sensor ischaracterized in that the sensor is equipped with a plurality of thesignal amplification wires to specify a position of radiation or lightbased on positions of the signal amplification wires which have detectedthe radiation or the light.

Effects of the Invention

According to the organic semiconductor radiation/light sensor of thepresent invention, the carriers created by passage of radiation or lightare avalanche-amplified by the high electric field generated near thesignal amplification wire by means of applying the high voltage to thesignal amplification wire, thus improving dramatically detectionefficiency. Hence, even radiation such as rays exhibiting low energyloss capability or the like can be detected in real time with highsensitivity. Besides, the organic semiconductor is low in cost and iseasy to deal with and further is flexible and therefore a radiationsensor applicable to new applications can be provided.

Further, the metal wire is used as the signal amplification wire. Hence,the organic semiconductor radiation/light sensor can be provided at lowcost.

Furthermore, the signal amplification wire is 10 to 100 m in diameter.Hence, the carriers created by the passage of radiation or light can becertainly avalanche-amplified and besides the organic semiconductorradiation/light sensor can be made easy to deal with in its fabricationand in its use.

Moreover, the organic semiconductor is any one of polyaniline,polythiophene and polypyrrole. Hence, the organic semiconductor sensorcan be provided at low cost.

Besides, the organic semiconductor is substantially columnar and thenthe signal amplification wire is arranged substantially parallel with abottom of the organic semiconductor and further the electrode formed bydeposition is provided on the upper surface of the organicsemiconductor. Hence, the organic semiconductor radiation/light sensorcan be provided which can be easily fabricated.

Further, the organic semiconductor is substantially columnar and thesignal amplification wire is arranged on a central axis of the organicsemiconductor and further the electrode formed by deposition is providedacross an entire circumference of a lateral face of the organicsemiconductor. Hence, an electric field within the sensor can be madeuniform, permitting the organic semiconductor sensor with highsensitivity to be provided.

Furthermore, the organic semiconductor is flat-plate-shaped and thesignal amplification wires are arranged substantially parallel with anupper surface of the organic semiconductor in a grid pattern and furtherthe electrode formed by deposition is provided across an entire uppersurface of the organic semiconductor. Hence, by observing a signalcoming from each of the signal amplification wires, information onpositions of the signal amplification wires which have detectedradiation or light can be obtained and then based on the information, aposition through which the radiation or the light has passed can bespecified as a point on a plane.

According to the radiation/light detector of the present invention,included is the organic semiconductor radiation/light sensor embeddedwith the signal amplification wire in the organic semiconductor. Hence,a radiation/light detector can be provided which can detect even β raysexhibiting low energy loss capability in real time with highsensitivity.

Further, by utilizing a metal wire as the signal amplification wire, theorganic semiconductor radiation/light detector can be provided at lowcost.

Furthermore, the signal amplification wire is 10 to 100 m in diameter.Hence, the carriers created by passage of radiation or light can becertainly avalanche-amplified and besides the radiation/light detectorcan be made easy to deal with in its fabrication and in its use.

Moreover, the organic semiconductor is any one of polyaniline,polythiophene and polypyrrole. Hence, the radiation/light detector canbe provided at low cost.

Further, the organic semiconductor is substantially columnar and thenthe signal amplification wire is arranged substantially parallel withthe bottom of the organic semiconductor and further the electrode formedby deposition is provided on the upper surface of the organicsemiconductor. Hence, the radiation/light detector can be provided whichcan be easily fabricated.

Furthermore, the organic semiconductor is substantially columnar and thesignal amplification wire is arranged on the central axis of the organicsemiconductor and further the electrode formed by deposition is providedacross an entire circumference of a lateral face of the organicsemiconductor. Hence, the electric field within the sensor can be madeuniform, permitting the radiation/light detector with high sensitivityto be provided.

Moreover, the organic semiconductor is flat-plate-shaped and the signalamplification wires are arranged substantially parallel with the uppersurface of the organic semiconductor in a grid pattern and further theelectrode formed by deposition is provided across the entire uppersurface of the organic semiconductor. Hence, by observing a signalcoming from each of the signal amplification wires, information onpositions of the signal amplification wires which have detectedradiation or light can be obtained and then based on the information, aposition through which the radiation or the light has passed can bespecified as a point on a plane.

Further, the organic semiconductor radiation/light sensor is equippedwith a plurality of the signal amplification wires to specify a positionof radiation or light based on positions of the signal amplificationwires which have detected the radiation or the light. Hence, regardlessof its simple structure, the sensor can detect a position of theradiation or light which has passed through the signal amplificationwires.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view illustrating an organic semiconductorradiation/light sensor according to a first embodiment of the presentinvention.

FIG. 2 is a side view illustrating the same.

FIG. 3 is a bottom plane view illustrating the same.

FIG. 4 is a graph illustrating output signals, observed by anoscilloscope, against rays' incidence measured using the organicsemiconductor radiation/light sensor according to the first embodimentof the present invention.

FIG. 5 is a graph illustrating a dependency of wave heights of theoutput signals described above on applied voltages.

FIG. 6 is a perspective view of an organic semiconductor radiation/lightsensor according to a second embodiment of the present invention.

FIG. 7 is a perspective view of an organic semiconductor radiation/lightsensor according to a fourth embodiment of the present invention.

DESCRIPTION OF NUMERAL SYMBOLS

-   1, 11, 21: organic semiconductor-   2, 12, 22 a, 22 b: signal amplification wire-   3, 13, 23: electrode

BEST MODE FOR CARRYING OUT THE INVENTION

Hereunder is a description of an embodiment of an organic semiconductorradiation/light sensor and a radiation/light detector according to thepresent invention with reference to the accompanying drawings.

(Embodiment 1)

In FIG. 1 to FIG. 3, a first embodiment of the organic semiconductorradiation/light sensor and the radiation/light detector according to thepresent invention are shown.

Numeral symbol 1 denotes an organic semiconductor formed in asubstantially columnar shape with 7 mm in diameter and 3 mm inthickness. In addition, the thicker the organic semiconductor 1, thelarger, the number of carriers created by passage of radiation or lightand thereby sensitivity of the organic semiconductor radiation/lightsensor becomes higher.

Part of a signal amplification wire 2 is embedded in the organicsemiconductor 1. This signal amplification wire 2 is arrangedsubstantially parallel with one surface of the organic semiconductor 1which is substantially columnar. In addition, in the present embodiment,for reasons of fabrication, the signal amplification wire 2 is embeddedin a biased position near one surface of the organic semiconductor 1. Toimprove uniformity of an electric field inside the sensor andsensitivity of the sensor, however, the signal amplification wire 2 isdesirably inserted into a central portion of the organic semiconductor1.

Here, as a material of the organic semiconductor 1, the material is notlimited to a specific one and therefore a conductive polymer moleculesuch as polyaniline, polythiophene, polypyrrole may be used. Desirably,however, polyaniline may be used due to its high solubility in asolvent, easy availability and inexpensiveness. In addition, thesolubility of polyaniline into NMP (N-methyl-2-pyrrolidone) is about 10%by mass. When conductive polymer molecules of a thiophene derivativesuch as polyalkylthiophene, polyethylenedioxithiophene are used, alow-polarity solvent such as toluene, xylene, chloroform, dichlomethaneis used in which these conductive polymer molecules are high dissoluble.Besides, these conductive polymer molecules can be also used in theirslurry states where they are not fully dissolved in a solvent. Materialof the organic semiconductor 1 is not specifically limited in itspurity.

As a material used for the signal amplification wire 2, any materialsmay be utilized if they are conductive and therefore the material is notconfined to a specific one. A metal wire, however, is suitably utilizedbecause it is easy to process in a uniform diameter and in considerationof its strength and its cost. In addition, in the present embodiment,utilized are polyaniline and a gold-plated tungsten wire with a circularcross section and a diameter of 30 m as the organic semiconductor 1 andthe signal amplification wire 2, respectively.

Further, a size of the signal amplification wire 2 is not specificallyconfined insofar as the size is sufficient to allow the carriers, whichhas been generated by the passage of radiation and light, to beavalanche-amplified and hence the size can be varied depending on avoltage applied to the signal amplification wire 2. The thinner thesignal amplification wire 2, the electric field near the signalamplification wire 2 gets higher in intensity to permit the avalancheamplification to be performed at a lower voltage. Hence, it is desirablethat the wire is thinner for attaining the avalanche amplification withcertainty. On the contrary, a certain magnitude of the size is requiredfor making the wire easy to deal with in fabricating and using theorganic semiconductor radiation/light sensor and for maintaining itsdurability. Accordingly, it is desirable that the size of the signalamplification wire 2 is 10 to 100 m. In addition, the diameter referredto here means an average diameter of the signal amplification wire 2 andwhen the cross section is not perfectly circular, a maximum diameter istaken.

Further, an electrode 3 formed by deposition is provided on the otherplane of the organic semiconductor 1 near which the signal amplificationwire 2 of the organic semiconductor 1 is not located. Gold is used as amaterial of the electrode 3, while the other metals are also usable. Alead wire 5 is fitted on the electrode 3 by using a conductive tape 4made up of copper. In addition, here, a gold-plated tungsten wire with adiameter of 150 m is used as the lead wire 5.

Next is a description of a method for fabricating the organicsemiconductor radiation/light sensor.

First, NMP (N-methyl-2-pyrodorine) solution of polyaniline is driedwithin a circular container with a diameter of 10 mm to fabricate asolid-state organic semiconductor 1. At this time, before polyaniline iscompletely dried, the gold-plated tungsten wire, acting as the signalamplification wire 2, with a diameter of 30 m is placed on thepolyaniline and then a polyaniline solution is added to be dried.

By this operation, the signal amplification wire 2 is embedded in theorganic semiconductor 1. In addition, when dried, the polyanilinesolution is put in a press container to be heated under pressure appliedand thereby it becomes easy to form thickly the organic semiconductor 1as well as being capable of drying the same at short times.

Next, after the polyaniline has been completely dried, an opposite planeof the organic semiconductor 1 to a plane where the signal amplificationwire 2 is embedded is subjected to a gold-plating process to form theelectrode 3. Then, the gold-plated tungsten wire with a diameter of 150m, acting as the lead wire 5, is attached to an upper plane of theelectrode 3 by using the conductive tape 4 made up of copper.

When the organic semiconductor radiation/light sensor according to thepresent embodiment is used, a voltage of 1 to 3 KV is applied across thesignal amplification wire 2 and the lead wire 5. The application of thehigh voltage like this collects, near the signal amplification wire 2,the carrier generated by the passage of radiation and light through theorganic semiconductor 1 and thereby the avalanche amplification ispracticed near the signal amplification wire 2. In addition, if theapplied voltage were too high, the organic semiconductor 1 would be ledto be damaged, while if the applied voltage were too low, the gain dueto the avalanche amplification would be low to degrade a signal-to-noiseratio (an S/N ratio). Hence, an appropriate voltage is desirably set inadvance.

The avalanche amplification increases the number of carriers, i.e., aquantity of output electric charge by a factor of several hundreds ormore. Thus, by applying a voltage to the signal amplification wire 2,the sufficient gain can be obtained by the avalanche amplification evenonly by means of the radiation/light sensor. Hence, the high-gainamplifier which has been mounted on the conventional inorganicsemiconductor radiation sensor can be replaced by a low-gain amplifieror further can be omitted. Consequently, the usage of the organicsemiconductor radiation/light sensor according to the present embodimentpermits a radiation/light detector to be realized at low cost.

In addition, for example, the conventional radiation detector equippedwith the inorganic semiconductor radiation sensor comprising a siliconPIN photodiode took advantage of no avalanche amplification and hence anamplifier with not less than thousands times as much high gain wasrequired.

Actually, the conventional amplifier using the silicon PIN photodiodewas mounted on the organic semiconductor radiation/light sensoraccording to the present embodiment to build up a radiation/lightdetector. The signal of rays obtained by successful observation usingthe radiation/light detector thus built up and the applied voltagedependence of wave heights of output signals are shown in FIG. 4 and inFIG. 5, respectively. Here, an area of the waveform shown in FIG. 4 andthe wave height shown in FIG. 5 are proportional to an amount of theelectric charge observed. In this manner, it has been verified that theorganic semiconductor radiation/light sensor according to the presentembodiment was extremely supersensitive since a faint signal wasamplified and observed by applying a high voltage.

In addition, the organic semiconductor radiation/light sensor accordingto the present embodiment can detect rays, γ rays, X-rays and neutronrays in addition to rays and further ultraviolet, visible and infraredrays and thus can be applied as an optical detector such as an opticalmonitor.

As described above, the organic semiconductor radiation/light sensoraccording to the present embodiment is embedded with the signalamplification wire 2 in the organic semiconductor 1 and then, thecarriers created by the passage of radiation or light areavalanche-amplified by the high electric field created near the signalamplification wire 2 by means of applying a high voltage to the signalamplification wire 2 and then, thus dramatically improving the detectionefficiency. Hence, even radiation such as rays exhibiting smaller energyloss capability can be detected in real time with high sensitivity.

Further, a metal wire is used as the signal amplification wire 2 andhence an organic semiconductor radiation/light sensor can be provided atlow cost.

Furthermore, the signal amplification wire 2 is 10 to 100 m in diameter.Hence, the carriers created by the passage of radiation or light can becertainly avalanche-amplified and besides the organic semiconductorradiation/light sensor can be made easy to handle in its fabrication andin its use.

Moreover, the organic semiconductor 1 is polyaniline. Hence, the organicsemiconductor radiation/light sensor can be provided at low cost.

Besides, the organic semiconductor 1 is substantially columnar and thesignal amplification wire 2 is arranged substantially parallel with thebottom face of the organic semiconductor 1 and further the electrodeformed by deposition is provided on the upper side of the organicsemiconductor 1. Hence, the organic semiconductor radiation/light sensorcan be provided which can be easily fabricated.

Further, the organic semiconductor radiation/light detector according tothe present embodiment is equipped with the organic semiconductorradiation/light sensor. Hence, the radiation/light detector can beprovided which can detect even radiation such as rays exhibiting smallerenergy loss capability in real time with high sensitivity.

(Embodiment 2)

In FIG. 6, shown is a second embodiment of an organic semiconductorradiation/light sensor according to the present invention.

Numeral symbol 11 denotes an organic semiconductor which is formed in along and substantially columnar shape and is 10 mm in diameter and 50 mmin thickness. Part of a signal amplification wire 12 is embedded in theorganic semiconductor 11. Then, the signal amplification wire 12 isarranged on a central axis of the organic semiconductor 11 which issubstantially columnar. In the present embodiment, as in the firstembodiment, polyaniline and a gold-plated tungsten wire with a circularcross section and 30 m in diameter are used for the organicsemiconductor 11 and the signal amplification wire 12, respectively.

Besides, there is provided an electrode 13 which is formed by applyinggold evaporation over an entire circumference in a lateral face of theorganic semiconductor 11 formed in the substantially columnar shape. Alead wire 15 is attached on the electrode 13 by using a conductive tapemade of copper.

When using the organic semiconductor radiation/light sensor according tothe present embodiment, a voltage of 1 to 3 KV is applied across thesignal amplification wire 12 and the lead wire 15. By applying the highvoltage like this, carriers created when radiation and light passthrough the organic semiconductor 11 are collected near the signalamplification wire 12 and thereby avalanche amplification is practicednear the signal amplification wire 12.

In the organic semiconductor radiation/light sensor according to thepresent embodiment, the signal amplification wire 12 is arranged in thecentral axis of the organic semiconductor 11 formed in the substantiallycolumnar shape and the electrode 13 is arranged in the lateral side ofthe organic semiconductor 11. Hence, an electric field inside the sensorcan be uniformalized and thereby the sensitivity of the sensor becomesexcellent.

As described above, the organic semiconductor radiation/light sensoraccording to the present embodiment is embedded with the signalamplification wire 12 in the organic semiconductor 11 and then, thecarriers created by the passage of radiation or light areavalanche-amplified by the high electric field created near the signalamplification wire 12 by means of applying the high voltage to thesignal amplification wire 12, thus dramatically improving the detectionefficiency. Hence, even radiation such as rays exhibiting smaller energyloss capability can be detected in real time with high sensitivity.

Further, the organic semiconductor 11 is substantially columnar and thesignal amplification wire 12 is arranged on the central axis of theorganic semiconductor 11 and further the electrode formed by depositionis provided across the entire circumference of the lateral face of theorganic semiconductor. Hence, the electric field within the sensor canbe made uniform, permitting the organic semiconductor radiation/lightsensor with high sensitivity to be provided.

(Embodiment 3)

Except that polyddecylthiophene (a test agent produced by Aldrich) hasbeen used instead of polyaniline for the organic semiconductor 11 in thesecond embodiment, in a third embodiment, the organic semiconductorradiation/light sensor has been made in the same way as was done in thesecond embodiment. Also in this organic semiconductor radiation/lightsensor, carriers created by passage of radiation or light areavalanche-amplified by a high electric field created near the signalamplification wire 12 by means of applying a high voltage to the signalamplification wire 12. Hence, as in the second embodiment, evenradiation such as rays exhibiting smaller energy loss capability can bedetected in real time with high sensitivity.

(Embodiment 4)

In FIG. 7, shown is a fourth embodiment of an organic semiconductorradiation/light sensor according to the present invention.

Numeral symbol 21 denotes an organic semiconductor radiation/lightsensor which is made from polyaniline and is formed in a flat plate 15mm square and 3 mm thick. A plurality of signal amplification wires 22a, 22 b are embedded in the organic semiconductor 21. The signalamplification wires 22 a, 22 b are both arranged substantially parallelwith an upper surface of the organic semiconductor 21 and further boththe wires 22 a, 22 b are arranged substantially perpendicularly to eachother without being contacted by each other. The plurality of the signalamplification wires 22 a are arranged at constant intervals of 1 mm andalso the same applies to the signal amplification wires 22 b. Thus, thesignal amplification wires 22 a, 22 b are arranged in a grid pattern.

Further, an electrode 23 formed by applying the gold evaporation over anentire area of an upper surface is provided on the top surface of theorganic semiconductor 21 formed in a flat-plate shape. On the electrode23, a lead wire 25 is attached with a conductive tape 24 made of copper.

When using the organic semiconductor radiation/light sensor according tothe present embodiment, a voltage of 1 to 3 KV is applied across thesignal amplification wires 22 a, 22 b and the lead wire 25. By applyingthe high voltage like this, the carrier generated by the passage ofradiation or light through the organic semiconductor 21 are collectednear the signal amplification wires 22 a, 22 b and then the avalancheamplification is performed near the signal amplification wires 22 a, 22b.

Here, in the present embodiment, the signal amplification wires 22 a, 22b are arranged in a grid pattern. Hence, by observing signals comingfrom each of the signal amplification wires 22 a, 22 b, information onpositions of the signal amplification wires 22 a, 22 b, where theradiation or the light has been detected can be obtained, thuspermitting the position where the radiation or the light has passedthrough to be specified as a point on a plane based on the information.

Then, using the organic semiconductor radiation/light sensor accordingto the present embodiment, the position of the radiation or the light isspecified based on the positions of the signal amplification wires 22 a,22 b where the radiation or the light has been detected and theradiation/light detector is built up so as to be capable of displayingthe position specified. As a result, the radiation/light detector can beutilized as, e.g., an X-ray location detection device such as a medicalCT scanner or the like. Further, by decreasing the intervals between thesignal amplification wires 22 a, 22 b, a position resolution ofradiation or light can be increased. In the case of the presentembodiment, the interval between the signal amplification wires 22 a, 22b is 1 mm and therefore the position resolution of radiation or lightresults in 1 mm or less. Consequently, a higher-resolutionradiation/light detector can be provided as compared to the conventionalCT scanner.

As described above, the organic semiconductor radiation/light sensoraccording to the present embodiment is embedded with the signalamplification wires 22 a, 22 b in the organic semiconductor 21 and then,the carriers created by the passage of radiation or light areavalanche-amplified by the high electric field created near the signalamplification wire 22 a, 22 b by means of applying the high voltage tothe signal amplification wire 22 a, 22 b, thus dramatically improvingthe detection efficiency. Hence, even radiation such as rays exhibitingsmaller energy loss capability can be detected in real time with highsensitivity.

Further, the organic semiconductor 21 is flat-plate-shaped and thesignal amplification wires 22 a, 22 b are arranged substantiallyparallel with the upper surface of the organic semiconductor in a gridpattern and further the electrode formed by deposition is providedacross the entire upper surface of the organic semiconductor 21. Hence,by observing a signal coming from each of the signal amplification wires22 a, 22 b, information on positions of the signal amplification wires22 a, 22 b which have detected radiation or light can be obtained andthen based on the information, a position through which the radiation orthe light has passed can be specified as a point on a plane.

Further, the organic semiconductor radiation/light sensor is equippedwith a plurality of the signal amplification wires 22 a, 22 b andthereby specifies the position of the radiation or the light based onthe positions of the signal amplification wires 22 a, 22 b which havedetected the radiation or the light. Hence, the position of theradiation or the light which has passed through the signal amplificationwires 22 a, 22 b can be detected even by this simple system.

In addition to this, the organic semiconductor radiation/light sensoruses an organic semiconductor, which is low in cost and is easy tohandle and besides is flexible and further can be bent if formed in asheet-like shape on the order of 100 m in thickness. Hence, aradiation/light sensor can be provided which is applicable to newapplications. Utilizing the feature of the organic semiconductor that isinexpensive and is flexible, a large-size and curved radiation/lightsensor can be manufactured. If inorganic crystalline semiconductors suchas silicon, germanium or the like which have features of high purity inmaterial, high cost and hardness were to be utilized, the sensor likethis would not be realized.

In addition, the present invention is not limited to the embodimentsdescribe above and various modifications are possible within departingthe gist of the present invention. The form of the organic semiconductoris not limited to one described above and can be accordingly alteredinto a form suitable for its use.

The organic semiconductor radiation/light detector according to thepresent invention is considered to be applicable to, e.g., the radiationmedicine field such as a position detector of X-rays in a CT scanner,the atomic field, and the space-related field and so on.

1. An organic semiconductor radiation/light detection method, comprising: providing an organic semiconductor with a single signal amplification wire that is embedded within the organic semiconductor and pierces through the organic semiconductor in a direction of diameter; creating carriers by passage of either radiation or light through the organic semiconductor; avalanche-amplifying the carriers by a high electric field created near the single signal amplification wire by applying a high voltage to the single signal amplification wire.
 2. The organic semiconductor radiation/light detection method according to claim 1, wherein said single signal amplification wire is a metal wire.
 3. The organic semiconductor radiation/light detection method according to claim 1, wherein said single signal amplification wire is 10 to 100 μm in diameter.
 4. The organic semiconductor radiation/light detection method according to claim 1, wherein said organic semiconductor is made of any one of polyaniline, polythiophene and polypyrrole.
 5. The organic semiconductor radiation/light detection method according to claim 1, further comprising: depositing an electrode on an upper surface of the organic semiconductor; wherein said organic semiconductor is substantially columnar, said single signal amplification wire is arranged substantially parallel with a bottom face of the organic semiconductor.
 6. The organic semiconductor radiation/light detection method according to claim 1, further comprising: depositing an electrode over an entire circumference of a lateral side of the organic semiconductor; wherein the organic semiconductor is substantially columnar, said signal amplification wire is arranged on a central axis of the organic semiconductor. 